What is the life expectancy of regular ethanol laced pump gas?
I’ve been fighting a drivability issue on my ‘83 F150. It has sat for several months, just moving around the property every once in a while as needed. A few days ago I needed to move it again and it wouldn’t start. The plugs were wet with fuel and smelled weird, so I put some fresh ones in but still no go. The cap and rotor looked great so I scrounged through my pile of HEI’s and found a very low mile (but probably close to 20 years old) Accel HEI and swiped the module out of it, and I had a barely used (also close to 20 year old) Mallory HEI coil laying around so I swapped in both at the same time. It fired right up, and idled great. But it had a terrible off idle stumble and was surging pretty bad going down the road. I switched to the rear tank, which was full but was last filled 3-4 months ago. Even after driving another 10 miles or so, drivability is still just as bad.
So...I’m wondering if the gas has went bad, or if I have some sort of compatibility issue with the coil and module?

It’s a mild 351w with an old 85 series Mallory HEI, in case your wondering how I used GM parts on this thing. The coil and module that was in it until today was OEM GM parts from a ‘77 350 Chevy HEI that I installed in this truck over 10 years ago, after the factory Mallory module disintegrated after only 1 year of daily driver useage

A couple of months is about it for it to be optimal as long it is sealed [tank or drum] ,depending on where you are in the world, fuels can be quite different between summer and winter. Typically colder winters will have an easier strike fuel, hotter summers will have fuel lock enhancement.

I would think the fuel will still be combustible to a point that an engine would start even after a quite lengthy period of time ,, but I'm sure there will be a lot more tech added to this!

my understanding is that down here in Arizona, it starts to go bad in 2 to 3 weeks if the car is not being used,, they say to think about it like using oil in a 2 stroke,, that the oil falls out of suspension and separates from the fuel without using the car or cycle so the movement keeps it mixed up,, same for the additives that they are putting in the fuel,, I do know that we get quite a few heads in with the valves and guides stuck with some nasty gum-me stuff on the stems and guides,,

After a little more troubleshooting tonight I think it’s time to open up the ancient 750 edelbrock. I’ve got very little fuel squirting out of the nozzles until half throttle or so.

The carb drying out I can see happening...kinda weird for the module or coil to fail too.

I have another old 600 edelbrock, but the inside of the bowls looks like someone was using it to smuggle coke with. I cleaned it out but it is heavily pitted everywhere...it’s junk

I’m in Texas, and it hasn’t gotten anywhere close to cold yet so we shouldn’t have any winter blend yet. I’ve was running on the front tank that I don’t even remember when I last filled it. It definitely smells worse than the rear tank

They go by dates only, AFAIK. What the weather actually does is of no consequence. Whether it gets cold in October or January, they still switch to the winter blend on a certain date AFAIK. There's a website with this info posted publicly just for this reason. For example, they can start selling winter ble d on Sept 15, despite it being 94* outside that day. If they want to sell it, that's all that needs to happen for them to be able to switch over. Still looking for that website. I can't recall where it was.

Ethanol [ like methanol ] will corrode alum because it absorbs water. It can make a real mess of an alum crab if it is left for weeks to evaporate. E fuel can also turn rubber fuel line into jelly. The rubber has to be E compatible.

They go by dates only, AFAIK. What the weather actually does is of no consequence. Whether it gets cold in October or January, they still switch to the winter blend on a certain date AFAIK. There's a website with this info posted publicly just for this reason. For example, they can start selling winter ble d on Sept 15, despite it being 94* outside that day. If they want to sell it, that's all that needs to happen for them to be able to switch over. Still looking for that website. I can't recall where it was.

My 2 cents is state to state it may vary and anything that sits longer than 3 weeks should get some stabil or other fuel treatment. I do that with my cars all the time due to things always taking longer than planned. Of course if longer and easy enough to I'll drain the fuel b4 it goes bad and use it in something else. I always forget to get some renegade gas for storage and some it's just easier to pour in some additive or drain.

I know as much as I can learn and try to keep an open mind to anything!

Damn pump gas is horrible, I can hear it pinging in hose as I pump it...

agree 100%,
after spending the last 18 months testing and tuning my street/strip 383 sbc reading spark plugs,using air/fuel sensors and i run my stuff fairly lean on the street to try and keep everything as clean as possible,decided to disassemble for upgrades and top of pistons,chambers and intake valves covered in this varnish crap and no its not oil from bad guides etc.
it is very disappointing,i can't tell you if our Australian 98 so called octane pump swill has ethanol
or not,maybe geoff2 might know that one,but i am looking for a different direction even have a thought of water/meth injection at least to try.

Every year when it comes time to store my Monte I add some Stabil and a bottle of gas line anti freeze.
I put this in before I drive to storage,about a half hour drive,and never have any problems with the gas going bad.
If I don't do this,like I did the first winter when I didn't know better,I will become familiar with cleaning carb jets until all the varnish is gone.
Guy

Every year when it comes time to store my Monte I add some Stabil and a bottle of gas line anti freeze.
...

You can save yourself considerable money by using just the active ingredient in Stabil and other fuel preservatives; Butylated hydroxytoluene (BHT). BHT is a petrochemical preservative (and also used in the food and health industry): https://en.wikipedia.org/wiki/Butylated_hydroxytoluene

Buy it in crystal form. Around 200mg (a bit under a tablespoon) treats 10 gallons of gasoline. I've been using it for years in the cars and the mowers.